BRPI0616688A2 - process of manufacturing a food or biotechnological product using a redox potential regulation - Google Patents

Abstract

Manufacture of a foodstuff or a biotechnological product, by fermentation in a medium (in which a control of redox potential of the medium is essential), comprises regulating a predetermined setpoint level of the redox potential of the medium by controlled addition of treatment gas to the medium and permitting the process to pass to the next level when the setpoint is reached.

Description

MANUFACTURING PROCESS OF AN OUBIOTECHNOLOGICAL FOOD PRODUCT USING A REDOX POTENTIAL REGULATION

The present invention relates to the field of food and biotechnology manufacturing processes using one or more fermentation steps.

The processes shown are very varied and can be divided into two large families:

- processes for the production of fermented food products, such as fermented milk products (yoghurts, white cheeses etc ...), fermented beverages (beers, wine etc ...),

- the processes for making biomass (lactic yeast, yeast, etc.) and metabolites (food ingredients, molecules of interest such as enzymes, amino acids, medicines, ethanol.......).

The invention proposes to new operating conditions which allow, as the case may be considered, to improve particularly the properties of the products thus manufactured, and especially their microbiological, sensory, physicochemical properties etc ..., or yields, purity etc ....

As we shall see in more detail below, the present invention proposes a new method of conducting such processes by controlling and regulating the redox potential of the medium at a given level of redox potential (redox level defined in each case to have an optimal desired effect). at one or more process key points, here by controlled additions of one or more gases or adapted gas mixtures.

Redox potential measurements can be obtained in a medium through any available medium, such as, for example, redox probes that allow direct and continuous measurements in liquid or semi-liquid media, or indirectly by gas content measurements. dissolved, for example, of hydrogen dissolved in the medium.

monitoring and regulation of the redox potential in certain key process steps allows, for example, to perform process steps or phases under stable reducing conditions or to alternate during the process of the steps into reducing conditions with steps under oxidizing conditions.

A condition is considered oxidizing or reducing in relation to the redox potential of the medium prior to gas adjustment. Thus a condition will be said to be reducing when the oxy-reduction potential will be less than the initial value before its adjustment and regulation (what potential if negative or not). Conversely, a condition will be said to be oxidizing when the oxy-reduction potential will be greater than the initial value prior to its adjustment and regulation (which potential reaches positive or not).

It will be recalled that oxide-reductions are the essential steps in anabolism and cell catabolism reactions, whereby the direction of exchange is determined by the oxide-reduction potential (hereinafter Eh). Eh is a state parameter of fermentations; Its variation alters the physicochemical environment of microorganisms. Metabolic activities and physiology of microorganisms are determined by intracellular pH (pHj.n) which will condition enzyme activity and accessibility of certain substrates and cofactors in metabolism reactions. PHin is a function of extracellular pH (pHex) and household-organism suitability. in maintaining a certain cellular homeostasis. The difference between pHin and pHex will also alter the value of the proto-motor force ΔμΗ +, which is especially implicated in the exchange of microbial cells with the exterior. The Eh and pHin parameters are closely linked, so the energy found in the high potential compounds such as adenosine triphosphate (ATP) and substrate gain can be used by the cell to maintain its pHin (and thus its ΔρΗ) thanks to the ATPases membranes.

According to Urbach et al in 1995 ("Contribution of lactic acid bacteria to flavor compound formation in dairy products", International Dairy Journal 5: 877-903), lactic bacteria are largely implicated in the manufacture of flavoring fermented milk products; they convert lactose to lactic acid; This leads to the production of diacetyl and acetaldehyde which are the main flavorings of fermented milk and fresh cheese.

Eh is an environmental parameter that may condition the metabolic activities of microorganisms and especially their ability to synthesize flavoring molecules. In particular, it was shown to the ementai and chedar that good quality cheeses had a low oxy-reduction potential.

Eh is a physicochemical parameter that, by its nature, acts on all media as long as it contains at least one molecule that can change from oxidized to reduced state and vice versa. This is why its effect is noticeable on all cellular functions.

Its action was shown on different types of bacterial strains, by way of illustration:

- The addition of chemical reducers in the culture media allowed to significantly alter growth and metabolic fluxes in Corynebacterium glutamicum, Clostridium acetobutylicum, Sporidiobolus ruinenii and Escherichia coli;

A gas-fixed reducing Eh allowed the metabolic fluxes in Saccharomyces cerevisiae to be altered with increased glycerol / ethanol ratio and accumulation of reserve sugars with increased yeast survival during storage.

In industrial environments, Eh is indirectly verified through oxygen whose inhibitory effect on lactic bacteria is well identified. This effect is due to its ability to synthesize cytochrome and heme nucleus enzymes.

It is further known that it is also possible to act on Eh to alter the survival of probiotic yeasts, metabolic fluxes, production and / or stability of flavoring molecules. The set of these results was obtained after a modification of the Eh by the own microorganisms, oxide-reducing molecules, or by heat treatment.

In the field of the use of gas mixtures in the lactic acid fermentation media, one can cite the works of Henriksen et al published in Letters in Applied Microbiology in 2000 (vol. 30 p415-418) which were interested in the growth of lactic acid bacteria, and showed that when cultures were swept away by nitrogen, growth was severely retarded, whereas the addition of minute amounts of CO2 in this case would initiate growth in exponential form.

The present invention then relates to a process for manufacturing a food or biotechnological product using one or more steps, one or more of the steps using a medium, one or more of the steps using a meiosis and a fermentation step, to the course of the process. process, lasting at least one of the process steps to a control operation of the redox potential of the medium considered, and characterized by conducting the process as follows:

- regulates at a predetermined reference level the redox potential of the stage medium whose redox potential is controlled by controlled additions of a detrimental gas to the medium under consideration, and

- allow the passage to the next stage of the step considered in the process when the reference value is reached,

to perform at least one of said reducing process steps and at least one of said oxidizing process steps.

It will be discussed indifferently in the following stages or stages that constitute the process, or phases that constitute a process stage.

The process according to the invention may further adopt one or more of the following technical characteristics:

- The process is a manufacturing process of a fermented dairy product, and the regulation of redox potential takes place in several of the steps in order to sequence oxidation and reduction steps as follows:

- Redox potential is adjusted to reduce conditions at one or more process points upstream of the pasteurization phase;

- Redox potential is adjusted to establish oxidizing conditions at one or more process points downstream of pasteurization.

- The process is a manufacturing process of a fermented dairy product, and the regulation of redox potential takes place in several of the steps in order to sequence oxidation and reduction steps as follows:

- Redox potential is adjusted to set oxidizing conditions at one or more process points upstream of the pasteurization phase;

- Redox potential is adjusted to reduce conditions at one or more process points downstream of pasteurization.

- the fermented milk product is a yogurt.

- said process conduction is carried out such that, for at least one of said defermentation steps, the control additions of a treatment gas allow to alternate the fermentation phases considered in reducing condition with the fermentation phases considered to be in oxidizing condition.

- The process is a brewing process, and the process conduction allows the redox potential regulation during fermentation to occur in two times: in the first time, the fermentation takes place in regulated oxidizing condition and in the presence of oxygen, to favor the growth of yeast and its good physiological state, and in a second time, the redox potential is reduced to an optimum value to allow the fermentation parameters as well as the sensory criteria to be improved.

The process is a fermentation fermentation process that aims at the manufacture of biomass and / or demetabolites, and the process conduction allows the redox potential of the medium to be regulated in different successive values as a function of the different phases of the fermentation to make a first phase under oxidizing conditions. in order to favor the growth of the microbial strain by oxidizing conditions, and after obtaining a maximum embryo mass content of transferring the fermenter under reducing conditions in order to initiate or intensify the production of one or more desired metabolites.

The process is a fermenting fermentation process aimed at the manufacture of biomass and / or demetabolites, and the conduction of this process allows to regulate the redox potential of the medium in different successive values as a function of the different stages of fermentation, in order to perform a first phase, which is slightly returned. reduction that is favorable to the growth of certain microorganisms and therefore the production of an important biomass followed by a more reducing phase which will allow the production of desired flavoring compounds to be favored.

The process is a fermentation fermenting process that aims at the manufacture of biomass and / or demetabolites, and the conduction of this process allows to change and control the redox potential of the medium. in a different amount for fermentation in order to adapt the metabolism or the physiology of the microorganisms to prepare them for a later stage.

The process is a fermentation fermenting process that aims at the manufacture of biomass and / or demetabolites, and the conduction of this process allows to change the redox potential level after the production of a desired metabolite to favor the excretion of the metabolite considered in the recovery medium.

The process is a fermenting fermentation process that aims at the manufacture of biomass and / or demetabolites, and the conduction of this process allows to change the level of redox potential after the production of a precursor of a molecule of interest to favor a chemical reaction that allows obtaining the wanted interest molecule.

- The process is a fermentation fermenting process aimed at the manufacture of biomass and / or demetabolites, and which subsequent to the fermentation are performed:

- the centrifugation, and / or filtration and / or ultrafiltration steps to recover the biomass produced, or

- purification steps on the fermentation medium to separate and concentrate metabolites,

and said conduction of the process allows to change the level of redox potential after separation of the medium containing the molecule of interest from the biomass (microbial cells) to favor the selective separation of the molecule of interest from the other meiprivileging compounds, for example, the fixation on a resin to be reduced form or oxidized form of the molecule of interest and its elution by an adapted solution.

Therefore, it is proposed to control the redoxem potential key places in the process, through everything available, such as redox probes. This control allows you to adjust the redox potential and master the addition of gases in the medium, accurately determining when the redox modification process can be stopped.

It is possible to envisage a system of automatic redox potential regulation of the medium, since it is known, for example, that certain microorganisms, by their activity, alter the redox potential of a medium. Thus it is allowed to store a stable redox for a given period of a fermentation.

It may also be possible, according to the process under consideration, to alternate between the phases of reducing and oxidizing conditions in order to favor the defined moments in the process of biochemical and / or biological reactions which, by their chaining, yields a product of definite characteristics. Thus, by way of illustration, it may be interesting to conduct a fermentation with a first so-called slightly reducing phase by addition of nitrogen (eliminating some of the dissolved oxygen) which is favorable to the growth of certain microorganisms and therefore the production of an important biomass followed by a more reducing phase. (e.g. through a hydrogen-containing mixture) which will allow, for example, to favor the production of desired flavoring compounds such as acetaldehyde produced by the lactic bacteria.

As will be understood from the above reading, the treatment gas should be chosen according to the process considered, the stage considered, the redox conditions to be achieved, and therefore a neutral gas such as nitrogen may be considered. Argon, helium, or carbon dioxide, or a gasoxidant such as oxygen or air, or a reducing gas like hydrogen, or a mixture of such gases.

Other features and advantages will emerge from the following description, given solely by way of example, especially with reference to the accompanying Figure 1 which illustrates an exemplary application of the invention in the case of a yoghurt or other fermented treat facility.

Recognizes on Figure 1 the following elements and steps:

- a milk preparation which generally comprises additions of components such as fat or protein or flavoring to fix the composition;

- a heating step;

- a pasteurization step (heat treatment);

- a homogenization (which may happen before or after pasteurization);

- cooling to the temperature at which inoculation will take place;

- inoculation with the desired strains;

- according to the type of yoghurt or fermented milk product considered: a fermentation in a tank followed by a pre-potting adjustment (eg "mixed" yoghurts), or the prior distribution of the mixed mixture into packaging where fermentation will take place (eg yoghurts "firm" or "dry");

a cooling of the products before their storage.

One can envisage how to do - a redox potential dimming to the following points of the chain:

(i) in the starting milk before normalization;

(j) in the milk mixture resulting from the addition of additional ingredients in milk;

(k) before or after the homogenization step of said milk mixture;

(l) before or after the pasteurisation stage of the myxalactea;

m) before or after the step of inoculation of the myxalatea with one or more strains of lactic acid bacteria;

n) before packing the product in the final packaging.

In accordance with the invention, in this case the manufacture of yoghurt or fermented milk products can be considered the sequencing of oxidation and reduction phases. Indeed, without being bound by the following explanation at some point, one may think that the reducing values may favorably shape the conformation of proteins, especially serum proteins rich in sulfur molecules. The redox potential allows to act on the state of these molecules which are either in the form of thiol clusters or in the form of disulfide bridges, and play a crucial role in protein formation after protein denaturation during the pasteurization step. The use of reducing conditions upstream of the pasteurisation phase will therefore enable this effect to be coupled to the effect of heat on proteins which will result in the creation of stable structure protein gels which would be particularly favorable to limit syneresis phenomena in yoghurts. Downstream of pasteurization, it will therefore be advantageous to establish less reducing redox values (or equal to the usual milk values) that will allow inoculated bacteria to develop normally without influencing their metabolism and thus without organoleptic consequence.

It may also be advantageous to adjust a potential redox target value during fermentation to voluntarily influence the metabolism of lactic yeast, and thus, for example, to direct the production of flavorings to the desired compounds.

Altering to finish the redox potential of the finished product to a more reducing value than the fermentation, the yogurt can be stabilized microbiologically and thus better preserve it from the eventual development of certain yeasts or molds.

It may be more particularly developed in the foregoing examples of yogurt making, but one may also refer to the manufacture of fermented beverages such as beer as well as the case of product production in fermenters. This is what will be done below.

Then the case of beer brewing was raised.

It will be shown below that in the case of brewing, it is interesting to make so that the redox potential regulation during fermentation takes place in two stages in two phases. In the first instance, the fermentation takes place advantageously under controlled oxidative condition in the presence of oxygen, to favor the growth of yeast and its good physiological state. In a second time, the redox potential is reduced to an optimum value to allow for improved fermentation parameters as well as sensory criteria (flavoring, foam consistency).

Remember that the brewing process behaves typically two stages of fermentation:

- The main fermentation: after ventilation of the yeast, it is inoculated with a Saccharomyces type yeast, which, by fermentation, turns the fermentable sugars into alcohol and carbon dioxide.

- Secondary fermentation or "guarding": This step develops after the preceding one by lowering the average temperature to near 0 ° C for a duration ranging from a few days to a few weeks. The young beer

will saturate in carbon dioxide, which contributes strongly to its sparkling character. It is also during this stage of maturation that the beer is clarified and its taste refined.

The following examples will show that it is advantageous to ferment the yeast for moments chosen in oxidizing condition and for moments chosen in reducing condition.

Example 1: Six yeast fermentation tests of the "Kirin" type were performed using a malt extract (this test is known to the man of the art, is a standalone preventive test ie disconnected from the brewing processoglobal): 2 yeasts of control (average redox potential: 400mV), 2 yeasts whose redox potential was reduced by an initial nitrogen bubble (average redox potential: 140mV), and 2 yeasts whose redox potential was reduced by an initial bubble with a denitrogen / hydrogen mixture (96 / 4) (average redox potential: 415mV). Yeasts were inoculated by a drying yeast at 11 106 viable cells per ml. The objective was to determine the influence of redox potential on yeast fermentative performance for 8 days at 8 ° C.

The following parameters were followed:

- the decrease in fermentable extract for 8 days,

- the evolution of fermenting yeast turbidity (yeast overgrowth) by measuring dolevedo optical density at 800nm for 8 days,

Fermentation parameters: apparent extract (fermentable extract plus non-fermentable extract) dolevedo for the test, apparent attenuation (percentage of fermentable extract used by yeast in relation to total yeast extract), degree of attenuation (ratio of fermentable extract used by yeast to extract) total fermentable).

The results (shown at table level 1) showed that lowering the redox potential of yeast causes an improvement in fermentation parameters: decreased apparent extract, increased attenuation and apparent attenuation, and increased optical density. These results reflect a more important use of fermentable sugars and a more important growth of yeast under more reducing conditions.

<table> table see original document page 16 </column> </row> <table>

Table 1: Average values of defermentation test results

Example 2: Six 30-liter micro-brew (beer brewing) tests were performed as follows: 2 airborne control yeasts (mean redox potential: 2 91 mV), 2 yeasts whose redox potential was induced by an initial nitrogen bubble (average redox potential: 216mV), and 2 yeasts whose redox potential was induced by an initial bubble with a hydrogen / hydrogen mixture (96/4) (average redox potential: -290mV). The beers thus obtained were analyzed. In short, the redox potential of yeast before heating is controlled, the rest of the manufacturing chain is traditional.

The results presented in table 2 show that changing the redox potential allows to improve the foam behavior. In fact, the more redox potential is lower the foam lasts a long time.

In addition, sensory analysis (performed as triangular tests) shows significant differences (at the 5% threshold) between the control beer and that obtained after the reduction of redox potential by the N2 / H2 mixture. The descriptors cited (oxidized, strong acidity) on the beer control denote a certain state of beer oxidation, more pronounced than on beer obtained with the mixture N2 / H2.

On the other hand, there is a slight tendency to increase the SO2 content of yeast beers with reduced redox potential by N2 or N2 / H2. The SO2 content generally increases due to the poor physiological state of yeast. The increase observed here is explained by the lack of yeast ventilation.

The reducing conditions therefore improved the sensory quality of the beer without, however, improving the fermentation parameters as described in example 1.

<table> table see original document page 17 </column> </row> <table>

Table 2: Beer analysis results (mean values of 2 repetitions for foam content, and values of 2 repetitions for SO2 content).

It has been well shown by what process in the case of brewing it is interesting to do so that the redox potential regulation during fermentation takes place in two times. In the first stage, fermentation takes place under regulated oxidative conditions and in the presence of oxygen, to favor yeast growth and its good physiological state. In a second time, the redox potential is reduced to an optimum value to improve fermentation parameters as well as sensory criteria (flavor, foam content).

We will now turn to the case of fermenting productions below.

In general, the production in fermenters responds to two distinct or simultaneous needs: the production of biomass and / or the production of molecules of interest. Several objectives can be pursued:

- biomass production,

- biomass production coupled with molecules of interest (primary metabolites),

- the production of molecules of interest other than those produced at the same time as biomass, called secondary metabolites,

- the chaining of biomass production after the molecules of interest.

There are different types of culture:

- the discontinued or batch culture for that half-culture provided at one time to the end, without providing or extracting medium during fermentation,

- semi-continuous or fed-batch cultivation, used for example for the production of substrate inhibition-sensitive biomass, and for the continuous or periodic nutrient supply to be coupled to growth without any continuous prevailing medium,

continuous culture by microorganisms that are kept in exponential growth phase by continuously providing a new medium which balances the continuous prevalence of the medium containing the suspended cells.

These fermentations, whether aerobic or anaerobic, take place in fermenter or bioreactor, with or without agitation, in a medium that the composition is defined to direct fermentation to the desired yield. Also, fermentation parameters such as pH, temperature, dissolved oxygen pressure, stirring speed, etc. . . they are usually set to predetermined optimum values in order to maximize demanded production.

It is said that the redox potential may be continuously evolving over the course of a fermentation for one or more of the following reasons:

- the growth of microorganisms,

- the production of oxidizing or reducing molecules by microorganisms,

- the supply of new culture medium for continuous and semi-continuous cultivation.

The present invention proposes to permanently control the redox potential and to regulate its optimum value by using controlled gas additions. This optimum value is experimentally predetermined in order to optimize the area sought at a certain moment of fermentation.

Advantageously, an adjustment of the redox potential of the culture medium provided in the case of semi-continuous and continuous cultures may or may not be associated with this regulation.

According to the aspects of the invention, the redox potential of the medium is regulated to different successive values as a function of different fermentation periods in order to guide the same to guide such desired reaction.

Fermentation can thus be regulated in a reducing condition in a first time after being regulated in a more oxidizing condition in a second time and inversely:

For example, one may choose to favor the growth of the microbial strain under oxidative conditions and then to obtain a maximum biomass content transferred to fermentation under more reducing conditions in order to begin to intensify the production of one or more demanded metabolites. For example, Saccharomyces is said to develop better under oxidizing conditions and to produce more glycerol under reducing conditions. Similarly, Corynebacterium glutamicum cultures are said to produce more amino acids under reducing conditions or that Sporidiobolus produces more of the flavoring compounds in reducing medium.

- It is also possible, by regulating the redox potential of the medium to a different value at the end of fermentation, to disrupt the metabolism or physiology of microorganisms.

to prepare them in a later step. It may therefore be of interest, for example, to produce Saccharomyeeseereeisiae in the presence of oxygen and to transfer the yeast-producing medium to an optimal reducing level in order to adapt it for future use, such as scavenging.

Fermentation can thus be conducted at 2 or 3 successive redox values, targeting only the most necessary ones. Thus, one can visualize the change in the level of regulation after the production of the desired metabolite (for example, the production of a parietal enzyme) prior to its production. harvesting or separation of the culture medium and thus for fermentation to favor excretion of the considered metabolite in a recovery medium. This change in redox potential can also intervene after the production of a precursor of the molecule of interest which under reduced conditions will lead to a chemical reaction allowing the molecule of interest to be obtained.

It is said that after the actual fermentation, various processes can be applied. The decentrifugation, filtration or ultrafiltration steps allow the recovery of the produced biomass. The purification steps may be performed on the fermentation medium to separate and concentrate the metabolites: centrifugation, filtration, chromatography, precipitation by addition of solvents, etc ...

The invention proposes to regulate redox to favor the separation of the molecules of interest. For example, production and / or excretion in the culture medium takes place under oxidizing (or reducing) condition, and is transferred under reducing (respectively oxidizing) condition to lead to the separation step. Thus, for example, a molecule may be melted onto a chromatography column by attaching to a resin under oxidizing condition and then released into a reducing elution solution.

If in the processes contemplated by the present invention it comprises one or several fermentation steps, the inoculation of the medium can be done directly, it can also be indirectly visualized by the fact that one or more pre-successive pre-cultures are performed in order to constitute the inoculation which will serve to inoculate the fermentation medium, and it may then also be visualized in accordance with the present invention to control and regulate the preculture redox potential by the controlled addition of a pre-culture medium treatment gas considered .

Claims (12)

1. A process for manufacturing a biotechnological food product, using one or more steps, one or more of the steps that use a medium, one or more steps that use a medium in a fermentation step in the course of which it takes at least one of the stages of the process a step redox potential control operation of the stage considered, and characterized by the fact that it conducts the process as follows: - it regulates to a predetermined redox opotential reference level of the step whose redox potential is controlled by controlled additions of a detrimental gas to the environment under consideration, the passage to the next stage of said process shall be authorized when the reference value is reached, so as to perform at least one of said process steps in a reducing condition and at least one of said process steps in oxidizing condition. Process according to Claim 1, characterized in that the process is a process for the manufacture of a fermented dairy product, and that the regulation of redox potential takes place in several of the steps in order to sequence the oxidation and reduction phases in the following manner. : - the redox potential is regulated to set reducing conditions at one or more process points upstream of the pasteurization phase - the redox potential is set to oxidizing conditions at one or more process points downstream of pasteurization. Process according to Claim 1, characterized in that the process is a process for the manufacture of a fermented dairy product and that the redox potential regulation takes place in several of the steps in order to sequence the oxidation and reduction phases as follows: - Redox potential is adjusted to set oxidizing conditions at one or more process points upstream of the pasteurization phase - Redox potential is set to reducing conditions at one or more process points located at the process point. downstream of pasteurization. Process according to either of Claims 2 or 3, characterized in that the fermented milk product is a yoghurt. Process according to Claim 1, characterized in that said process conduction is carried out such that, for at least one of said fermentation steps, the controlled additions of a treatment gas allow alternation of the defermentation phases considered in the condition. reduced with the fermentation phases considered under oxidizing conditions. Process according to Claim 5, characterized in that the process is a brewing process and said process conduction allows the regulation of the redox potential during fermentation to take place in two stages: Fermentation takes place in a regulated oxidizing condition and in the presence of oxygen, to favor the growth of yeast and its good physiological state, and it was a second time, the redox potential is reduced to an optimum value to allow to improve the fermentation parameters as well as the sensory criteria. Process according to claim 5, characterized in that the process is a fermenter defermentation process for the manufacture of biomass and / or metabolites, and that said process conduction allows to regulate the redox potential of the medium in different values. successive depending on the different stages of fermentation in order to carry out a first phase under oxidizing conditions in order to favor microbial growth under oxidizing conditions, and after obtaining a maximum biomass content of transferring the fermenter under reducing conditions in order to initiate or intensify the production. of one or more metabolites sought. Process according to Claim 5, characterized in that the process is a fermenter defermentation process aimed at the manufacture of biomass and / or metabolites, and that said process conduction allows to regulate the redox potential of the medium by different values. depending on the different stages of fermentation, in order to make a slightly reduced first stage that is favorable to the growth of certain microorganisms and therefore the production of an important biomass, followed by a more reducing phase that will allow the production of desired flavoring compounds to be favored. . Process according to Claim 5, characterized in that the process is a fermenter defermentation process aimed at the manufacture of biomass and / or metabolites, and that said process conduction allows to alter and regulate the redox potential of a different value for fermentation in order to decapitate the metabolism or physiology of microorganisms for the preparation of a later stage. Process according to Claim 5, characterized in that the process is a fermenter defermentation process aimed at the manufacture of biomass and / or metabolites, and that said process conduction allows to change the level of redox potential after production. of a desired metabolite to favor the excretion of the metabolite considered in the recovery medium. Process according to Claim 5, characterized in that the process is a fermenter defermentation process aimed at the manufacture of biomass and / or metabolites, and that said process conduction allows to change the level of redox potential after production. of a precursor of a molecule of interest to favor a chemical reaction that enables the desired molecule of interest to be obtained. Process according to any one of claims 5, 6, 7, 8, 9, 10 or 11, characterized by the fact that the process is a fermentation fermenting process which aims at the manufacture of biomass and / or demetabolites, and which subsequently fermentation are carried out: - the centrifugation, and / or filtration and / or ultrafiltration steps to recover the produced biomass, or - the purification steps on the fermentation medium to separate and concentrate metabolites, and that said conduction of the process allows for alteration of the process level of redox potential after separation of the medium containing the molecule of interest from the biomass to favor selective separation of the molecule of interest from other medium compounds privileging for example the fixation on a resin either in reduced form or in oxidized form of the molecule of interest and its elution by an adapted solution.